There will be a Z-shaped legendary
This one makes a lot of sense. Yevetal is Y-shaped, and Xerneas looks like an X (more or less). Its only reasonable that the third mystery legendary would resemble the letter Z, right? Wrong. In the end, we got a giant green slug thing called Zygarde, but fan art of the theorized Pokmon still turned out pretty cool.
Your rival is a journalist
While the crazy time-traveling shenanigans were occurring, your rival and magazine writer Ricki was apparently going to journey across the region and document the occurrences. Also, the Pokmon professor was supposed to be named Bristle instead of the Sycamore we know and love.
The Champion is your father
In a climactic twist, Mr. XY said that the final Champion of the Elite Four was to be your very own father, a fact that wasnt supposed to be revealed until the very end. You meet him in the past only to take him down in the present. Spoiler alert!
A Dragon type Eeveelution is coming
The Village of Dragons is a canonical location thats said to exist near the Unova region in the anime. However, when talking to a certain NPC in X and Y near Lumiose City who gives the player the TM Dragon Tail, he mentions the village, which got some people thinking: What if DLC allows players to go to the Village of Dragons, and what if you can take an Eevee there to evolve it into a Dragon type? Its too bad Nintendo has come out and said theyre not publishing any DLC for the games, disproving this stretch of a rumor.
Much of the new Pokdex is going to be baby Pokmon or evolutions of existing Pokmon
One of the hardest rumors to swallow was the idea that the Pokdex would only include 99 new Pokmon, with a good chunk of them being new evolutions of existing ones. While there actually ended up being less than 70 new Pokmon at launch, at least theyre all completely original.
There is going to be a Pokmon named Toilelite...
Mr. XY actually took the time to fabricate a somewhat believable Pokdex, but some red flags went up at some of the Pokmons names. For instance, he named Houndooms evolution Houndoomed, the early game Normal type he called Dogsnout, and one mysterious Pokmon he went so far as to dub Toilelite. Ill let you imagine what that thing was going to look like.
...as well as a coconut soldier Pokmon
Besides just naming the Pokmon, this insider shared descriptions of the designs for some of the upcoming Pokmon. He claimed wed get one called Cocomando, which was going to be a coconut-based soldier. There was supposedly going to be a Fighting type Pokmon that resembled a giant, sentient sneaker as well. Sounds weird until you remember how strange official Pokmon designs can get.
Oh, and the Pokdex itself? Its awesome now
The Pokdex was going to be a 3D tablet that included basic things such as Pokmon models, locations, cries, stats, and so on, just like in every other game. What was rumored to be included were full paragraph descriptions of each Pokmon and even comments on each species left by players from around the world.
There are going to be some crazy type combos
While Pokmon X and Y did introduce unusual type combinations, such as Hawluchas Fighting/Flying type, Mr. XY insisted that the games would introduce a plethora of new combos such a Dark/Electric, Grass/Dragon, and even Fire/Ice in the form of Darmanitans new evolution, Snomanitan.
The four legendary Pokmon are based on card suits
A rumor that held some promise was the idea of a set of legendary Pokmon based on a deck of playing cards, each one representing a different suit. There was going to be a cobra with a heart-shaped hood and tail, a tiger with diamond patterns, a t-rex with spade-shaped eyes, and a peacock with a club-shaped tail. Doesn't really line up with the X/Y thing, but it's neat nonetheless.